title: Up-regulation of Fas ligand expression by sirtuin 1 in both flow-restricted vessels and serum-stimulated vascular smooth muscle cells.
abstract: OBJECTIVE
  To study the role of sirtuin 1 (SIRT1) in Fas ligand (FasL) expression regulation during vascular lesion formation and to elucidate the potential mechanisms.
  
  
  METHODS
  SIRT1 and FasL protein levels were detected by Western blotting in either mouse arteries extract or the whole rat aortic vascular smooth muscle cell (VSMC) lysate. Smooth muscle cell (SMC)-specific human SIRT1 transgenic (Tg) C57BL/6 mice and their littermate wild-type (WT) controls underwent complete carotid artery ligation (ligation groups) or the ligation-excluded operation (sham groups). The carotid arteries were collected 1 day after operation. Reverse transcription-polymerase chain reaction was performed to detect the mRNA levels of SIRT1 and FasL. Luciferase reporter assays were performed to detect the effect of WT-SIRT1, a dominant-negative form of SIRT1 (SIRT1H363Y), and GATA-6 on the promoter activity of FasL. Flow cytometry assay was applied to measure the hypodiploid DNA content of VSMC so as to monitor cellular apoptosis.
  
  
  RESULTS
  SIRT1 was expressed in both rat aortic VSMCs and mouse arteries. Forced SIRT1 expression increased FasL expression both in injured mouse carotid arteries 1 day after ligation (P<0.001) and VSMCs treated with serum (P<0.05 at the transcriptional level, P<0.001 at the protein level). No notable apoptosis was observed. Furthermore, transcription factor GATA-6 increased the promoter activity of FasL (P<0.001). The induction of FasL promoter activity by GATA-6 was enhanced by WT-SIRT1 (P<0.001), while SIRT1H363Y significantly relieved the enhancing effect of WT-SIRT1 on GATA-6 (P<0.001).
  
  
  CONCLUSIONS
  Overexpression of SIRT1 up-regulates FasL expression in both flow-restricted mouse carotid arteries and serum-stimulated VSMCs. The transcription factor GATA-6 participates in the transcriptional regulation of FasL expression by SIRT1.
authors.affiliation: Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Peng
authors.initials: P
authors.lastname: Gao
authors.forename: Hou-zao
authors.initials: HZ
authors.lastname: Chen
authors.forename: Zhu-qin
authors.initials: ZQ
authors.lastname: Zhang
authors.forename: Ting-ting
authors.initials: TT
authors.lastname: Xu
authors.forename: Yu-yan
authors.initials: YY
authors.lastname: Jia
authors.forename: Hui-na
authors.initials: HN
authors.lastname: Zhang
authors.forename: Guan-hua
authors.initials: GH
authors.lastname: Du
authors.forename: De-pei
authors.initials: DP
authors.lastname: Liu
mesh_terms: D000818:Animals; D017209:Apoptosis; D002339:Carotid Arteries / Q000502:physiology; D053222:Fas Ligand Protein / Q000235:genetics*; D050993:GATA6 Transcription Factor / Q000502:physiology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D056564:Sirtuin 1 / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D053222:Fas Ligand Protein; D050993:GATA6 Transcription Factor; D012333:RNA, Messenger; D056564:Sirtuin 1